The invention concerns a method and device for monitoring negative pressure loss in a negative pressure generating device, in particular an ejector.
There are a plurality of conventional ejectors, which are generally used to generate an negative pressure using compressed air. Ejectors are highly advantageous in that they can be connected to the generally existing compressed air network and therefore require no negative pressure lines. The ejectors are supplied with compressed air and generate the negative pressure in accordance with the Venturi principle. They are generally located directly in that area where the negative pressure is required. For this reason, long negative pressure channels needing permanent evacuation are not required, since an negative pressure can be immediately provided using ejectors.
There are conventional negative pressure gripping devices comprising several grippers which are independent of each other, each of which must be supplied with an negative pressure. This requires a corresponding number of ejectors. The compressed air lines must be guided to these ejectors and the negative pressure channels must be connected to the suction grippers. This is often difficult and can be realized only with a plurality of air tubes. When replacing an ejector for maintenance and/or repair, the tubing must generally be released and the electric connections be disconnected before the ejector can be removed from the connection.
DE-T-692 29 120 discloses a receiving device for an ejector having a centralized pressurized air supply. DE-U-201 20 609 discloses an ejector having an analysis device for determining wear by measuring working cycles. The number of working cycles can, however, only provide an empirical indication of possible wear. The actual wear could lead to a substantially earlier or later failure. Moreover, the state of components outside of the ejector, such as feed and exhaust lines, cannot be monitored.
It is the underlying purpose of the invention to provide a device with a simpler design and with which defects can be more easily determined.